release/src-rt-6.x.4708/linux/linux-2.6.36/block/blk-lib.c

   1 /*
   2  * Functions related to generic helpers functions
   3  */
   4 #include <linux/kernel.h>
   5 #include <linux/module.h>
   6 #include <linux/bio.h>
   7 #include <linux/blkdev.h>
   8 #include <linux/scatterlist.h>
   9
  10 #include "blk.h"
  11
  12 static void blkdev_discard_end_io(struct bio *bio, int err)
  13 {
  14         if (err) {
  15                 if (err == -EOPNOTSUPP)
  16                         set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
  17                 clear_bit(BIO_UPTODATE, &bio->bi_flags);
  18         }
  19
  20         if (bio->bi_private)
  21                 complete(bio->bi_private);
  22
  23         bio_put(bio);
  24 }
  25
  26 /**
  27  * blkdev_issue_discard - queue a discard
  28  * @bdev:       blockdev to issue discard for
  29  * @sector:     start sector
  30  * @nr_sects:   number of sectors to discard
  31  * @gfp_mask:   memory allocation flags (for bio_alloc)
  32  * @flags:      BLKDEV_IFL_* flags to control behaviour
  33  *
  34  * Description:
  35  *    Issue a discard request for the sectors in question.
  36  */
  37 int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
  38                 sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
  39 {
  40         DECLARE_COMPLETION_ONSTACK(wait);
  41         struct request_queue *q = bdev_get_queue(bdev);
  42         int type = flags & BLKDEV_IFL_BARRIER ?
  43                 DISCARD_BARRIER : DISCARD_NOBARRIER;
  44         unsigned int max_discard_sectors;
  45         struct bio *bio;
  46         int ret = 0;
  47
  48         if (!q)
  49                 return -ENXIO;
  50
  51         if (!blk_queue_discard(q))
  52                 return -EOPNOTSUPP;
  53
  54         /*
  55          * Ensure that max_discard_sectors is of the proper
  56          * granularity
  57          */
  58         max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
  59         if (q->limits.discard_granularity) {
  60                 unsigned int disc_sects = q->limits.discard_granularity >> 9;
  61
  62                 max_discard_sectors &= ~(disc_sects - 1);
  63         }
  64
  65         if (flags & BLKDEV_IFL_SECURE) {
  66                 if (!blk_queue_secdiscard(q))
  67                         return -EOPNOTSUPP;
  68                 type |= DISCARD_SECURE;
  69         }
  70
  71         while (nr_sects && !ret) {
  72                 bio = bio_alloc(gfp_mask, 1);
  73                 if (!bio) {
  74                         ret = -ENOMEM;
  75                         break;
  76                 }
  77
  78                 bio->bi_sector = sector;
  79                 bio->bi_end_io = blkdev_discard_end_io;
  80                 bio->bi_bdev = bdev;
  81                 if (flags & BLKDEV_IFL_WAIT)
  82                         bio->bi_private = &wait;
  83
  84                 if (nr_sects > max_discard_sectors) {
  85                         bio->bi_size = max_discard_sectors << 9;
  86                         nr_sects -= max_discard_sectors;
  87                         sector += max_discard_sectors;
  88                 } else {
  89                         bio->bi_size = nr_sects << 9;
  90                         nr_sects = 0;
  91                 }
  92
  93                 bio_get(bio);
  94                 submit_bio(type, bio);
  95
  96                 if (flags & BLKDEV_IFL_WAIT)
  97                         wait_for_completion(&wait);
  98
  99                 if (bio_flagged(bio, BIO_EOPNOTSUPP))
 100                         ret = -EOPNOTSUPP;
 101                 else if (!bio_flagged(bio, BIO_UPTODATE))
 102                         ret = -EIO;
 103                 bio_put(bio);
 104         }
 105
 106         return ret;
 107 }
 108 EXPORT_SYMBOL(blkdev_issue_discard);
 109
 110 struct bio_batch
 111 {
 112         atomic_t                done;
 113         unsigned long           flags;
 114         struct completion       *wait;
 115         bio_end_io_t            *end_io;
 116 };
 117
 118 static void bio_batch_end_io(struct bio *bio, int err)
 119 {
 120         struct bio_batch *bb = bio->bi_private;
 121
 122         if (err) {
 123                 if (err == -EOPNOTSUPP)
 124                         set_bit(BIO_EOPNOTSUPP, &bb->flags);
 125                 else
 126                         clear_bit(BIO_UPTODATE, &bb->flags);
 127         }
 128         if (bb) {
 129                 if (bb->end_io)
 130                         bb->end_io(bio, err);
 131                 atomic_inc(&bb->done);
 132                 complete(bb->wait);
 133         }
 134         bio_put(bio);
 135 }
 136
 137 /**
 138  * blkdev_issue_zeroout generate number of zero filed write bios
 139  * @bdev:       blockdev to issue
 140  * @sector:     start sector
 141  * @nr_sects:   number of sectors to write
 142  * @gfp_mask:   memory allocation flags (for bio_alloc)
 143  * @flags:      BLKDEV_IFL_* flags to control behaviour
 144  *
 145  * Description:
 146  *  Generate and issue number of bios with zerofiled pages.
 147  *  Send barrier at the beginning and at the end if requested. This guarantie
 148  *  correct request ordering. Empty barrier allow us to avoid post queue flush.
 149  */
 150
 151 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 152                         sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
 153 {
 154         int ret;
 155         struct bio *bio;
 156         struct bio_batch bb;
 157         unsigned int sz, issued = 0;
 158         DECLARE_COMPLETION_ONSTACK(wait);
 159
 160         atomic_set(&bb.done, 0);
 161         bb.flags = 1 << BIO_UPTODATE;
 162         bb.wait = &wait;
 163         bb.end_io = NULL;
 164
 165         if (flags & BLKDEV_IFL_BARRIER) {
 166                 /* issue async barrier before the data */
 167                 ret = blkdev_issue_flush(bdev, gfp_mask, NULL, 0);
 168                 if (ret)
 169                         return ret;
 170         }
 171 submit:
 172         ret = 0;
 173         while (nr_sects != 0) {
 174                 bio = bio_alloc(gfp_mask,
 175                                 min(nr_sects, (sector_t)BIO_MAX_PAGES));
 176                 if (!bio) {
 177                         ret = -ENOMEM;
 178                         break;
 179                 }
 180
 181                 bio->bi_sector = sector;
 182                 bio->bi_bdev   = bdev;
 183                 bio->bi_end_io = bio_batch_end_io;
 184                 if (flags & BLKDEV_IFL_WAIT)
 185                         bio->bi_private = &bb;
 186
 187                 while (nr_sects != 0) {
 188                         sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
 189                         if (sz == 0)
 190                                 /* bio has maximum size possible */
 191                                 break;
 192                         ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
 193                         nr_sects -= ret >> 9;
 194                         sector += ret >> 9;
 195                         if (ret < (sz << 9))
 196                                 break;
 197                 }
 198                 ret = 0;
 199                 issued++;
 200                 submit_bio(WRITE, bio);
 201         }
 202         /*
 203          * When all data bios are in flight. Send final barrier if requeted.
 204          */
 205         if (nr_sects == 0 && flags & BLKDEV_IFL_BARRIER)
 206                 ret = blkdev_issue_flush(bdev, gfp_mask, NULL,
 207                                         flags & BLKDEV_IFL_WAIT);
 208
 209
 210         if (flags & BLKDEV_IFL_WAIT)
 211                 /* Wait for bios in-flight */
 212                 while ( issued != atomic_read(&bb.done))
 213                         wait_for_completion(&wait);
 214
 215         if (!test_bit(BIO_UPTODATE, &bb.flags))
 216                 /* One of bios in the batch was completed with error.*/
 217                 ret = -EIO;
 218
 219         if (ret)
 220                 goto out;
 221
 222         if (test_bit(BIO_EOPNOTSUPP, &bb.flags)) {
 223                 ret = -EOPNOTSUPP;
 224                 goto out;
 225         }
 226         if (nr_sects != 0)
 227                 goto submit;
 228 out:
 229         return ret;
 230 }
 231 EXPORT_SYMBOL(blkdev_issue_zeroout);